1. Field of the Invention
The present invention relates to a dielectric film and to a process for its fabrication. A application Ser. No. 11/492,943 filed Jul. 26, 2006, issued as U.S. Pat. No. 7,539,005 on May 26, 2009 is related to the present application. The disclosure of the prior application is hereby incorporated herein by reference in its entirety.
2. Related Background Art
Solution methods are known as methods for forming dielectric films containing metal oxides such as barium strontium titanate (BST) on metal layers. In such solution methods, a solution containing prescribed starting materials is coated onto a metal layer and dried, and the formed precursor layer is baked to form a dielectric film. However, when the metal composing the metal layer is a readily oxidizing metal such as Cu or Ni, the metal layer becomes oxidized during the baking, thereby losing conductivity. When oxidation of the metal occurs, even if the dielectric constant of the dielectric layer itself is increased, for example, the capacity of the capacitor does not adequately increase. In order to prevent oxidation of the metal layer, therefore, there have been proposed methods such as a method of providing a buffer layer on the metal layer (W. Fan et al., Journal of Applied Physics, Vol. 94, No. 9, p. 6192), and methods of accomplishing the baking in a reducing environment such as H2O/H2 mixed gas or the like (Brian Laughlin et al., 2003 MRS Fall Meeting, Symposium C, 2003, p. 70; Jeff Dawley et al., 2003 MRS Fall Meeting, Symposium C, 2003, p. 70; R. J. Ong, J. Mater. Res., 2003, Vol. 18, No. 10, p. 2310).
The following publications are also concerned with formation of dielectric films: Jon-Paul Maria et al., J. Am. Ceram. Soc., Vol. 84, No. 10, p. 2436; Y. Fujisaki et al., Jpn. J. Appl. Phys., 2003, Vol. 42, p. L267; Y Fujisaki et al., Jpn. J. Appl. Phys., 2002, Vol. 41, p. L1164; and Japanese Patent Publication No. 3188179.